Aaron Ramsey made his first competitive senior appearance since suffering a broken leg in a challenge with Stoke's Ryan Shawcross nine months ago but could do nothing to help Nottingham Forest avoid a derby defeat.
The 19-year-old Welsh international, who returned to action with Arsenal's reserves last week, played the final 30 minutes in the first match of his six-week loan spell with the Midlands side.
"He is a couple of weeks away from being fully fit and we know we have to be careful with him but you could see his quality from the moment he stepped on the field," Forest manager Billy Davies said.
Davies argued that Forest should have had a second-half penalty for a trip on Rob Earnshaw by Leicester's Jack Hobbs. "I spoke to the referee when we came off and he agreed he got it wrong," he said. "It was a massive turning point."
However, Davies did not argue with Leicester manager Sven-Goran Eriksson's view that Leicester were good value for their fifth win in nine Championship matches since the Swede took charge, in which Andy King's 59th-minute goal proved the decisive moment. "We did not compete well enough or pass well enough," Davies said. "We deserved nothing."
After a cagey opening, Dele Adebola should have put Forest in front from a Garath McCleary cross on 21 minutes. But for the most part, Leicester posed the bigger threat and they were unlucky not to go ahead when Luke Chambers somehow denied the on-loan debutant Roman Bednar on the line.
Chambers then almost diverted Greg Cunningham's free kick into his own net as an attempted clearance skimmed off his head, although he came to Camp's aid just before half-time, hacking the ball off the line after Darius Vassell's poke squeezed past the Forest keeper.
Forest survived more scares at the start of the second half when Camp denied Richie Wellens and Leicester had as good a shout for a penalty of their own when Chris Cohen manhandled Vassell. Forest's resistance cracked when Vassell slid the ball sideways for King to score his eighth goal of the season.
"I don't know if Forest should have had a penalty but I felt on chances and possession we deserved to win," Eriksson said, revealing that Chris Kirkland, who he has taken on loan from Wigan, could not make his debut after suffering a new back problem in training.
Leicester City (4-4-2): Weale; Naughton, Davies, Hobbs, Cunningham; King. Abe, Wellens, Gallagher (Waghorn, 89); Vassell (Dyer, 72), Bednar (Howard, 80). Substitutes not used Morrison, Oakley, Fryatt, Logan (gk).
Nottingham Forest (4-2-3-1): Camp; Gunter, Morgan, Chambers, Bertrand; Moussi, Cohen (Ramsey, 61); McCleary, McGugan (Tyson, 68), Anderson; Adebola (Earnshaw, 36). Substitutes not used Wilson, Tudgayu, Smith (gk), Majewski.
Referee M Oliver (Northumberland).